regmap: spi: Handle async writes of only one buffer
If the value is zero then assume it has been included in the register data
and don't send anything, minimising the number of interactions with the
hardware.
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/base/regmap/regmap-spi.c b/drivers/base/regmap/regmap-spi.c
index 4c506bd..37f12ae 100644
--- a/drivers/base/regmap/regmap-spi.c
+++ b/drivers/base/regmap/regmap-spi.c
@@ -73,7 +73,8 @@
spi_message_init(&async->m);
spi_message_add_tail(&async->t[0], &async->m);
- spi_message_add_tail(&async->t[1], &async->m);
+ if (val)
+ spi_message_add_tail(&async->t[1], &async->m);
async->m.complete = regmap_spi_complete;
async->m.context = async;